Abstract: A control system for construction machinery, includes a hydraulic pump, at least one control valve installed in a center bypass line connected to the hydraulic pump and configured to control a flow direction of a working oil discharged from the hydraulic pump to selectively supply the working oil to an actuator, a bypass control valve installed downstream from the control valve in the center bypass line to variably control an amount of the working oil draining to a drain tank through the center bypass line, and a controller configured to control operations of the hydraulic pump and the bypass control valve according to a manipulation signal of an operator and to open the bypass control valve according to pump peak occurrence to reduce a pump peak.

Abstract: A directional control valve including a force-regulated magnet, a control piston, an actuating piston, first and second elastic elements and a conductor. The control piston is displaceable using the force-regulated magnet, the control piston varies the flow cross-section between pressure, piston, and tank connections. The actuation piston has a first and second chamber. The first elastic element acts against a hydraulic pressure in the first chamber. The actuating piston being connected to the control piston by the first elastic element. The second elastic element acts against the hydraulic pressure in the first chamber. The actuating piston being connected by the second elastic element to the control housing or the flange. The conductor is connected to the electromagnet for control of the electromagnet such that the magnetic force and the position of the control, the actuating, and the pilot pistons are regulated by a voltage generated in the conductor.

Abstract: A method of operating a control valve assembly for a hydraulic system includes detecting the current operation of a first position sensor and a second position sensor to determine if at least one of the first position sensor and the second position sensor is inoperable. A pressure of the fluid at a first work port and a second work port is measured, and one of a first valve and a second valve is actuated when one of the first position sensor and the second position sensor is determined to be inoperable. The first valve is actuated based upon the fluid pressure measured at the second work port to adjust the flow of the fluid through the first work port. The second valve is actuated based upon the fluid pressure measured at the first work port to adjust the flow of the fluid through the second work port.

Abstract: A control device for the position control of a hydraulic cylinder unit has a controller which receives a set and an actual piston position and determines a preliminary manipulated variable based on the difference of the set and actual positions. A linearization unit multiplies the variable with a linearization factor and outputs it to the valve control unit so that the piston is adjusted at an adjustment speed. The linearization unit determines the factor dynamically as a function of the actual piston position and of working pressures that prevail at both piston sides. The linearization factor is determined such that a ratio of the adjustment speed to the difference of the set and actual positions is independent of the actual position and the working pressures. In the specific case where the controller is configured as a P controller, the order of the controller and the linearization unit can be reversed.

Abstract: A valve arrangement includes a valve member, which rotates continuously in one sense. The generally cylindrical head of the valve member, within the housing, is formed to co-operate with various ports to create reciprocation in the actuator. It is preferred to provide some vibration of the valve member, to assist in overcoming the effects of friction.

Abstract: A valve that keeps a electro-hydraulic servo valve (EHSV) controlled device such as a fuel metering valve or actuator at the last commanded position upon loss of input command in the EHSV is described. The valve fixes the position of the positioning device within a tolerance of the position the positioning device was at prior to the loss of the position command.

Abstract: Disclosed is a hydraulic control circuit and method thereof for reducing heat generation and energy losses caused by overload.

Abstract: A positioner for a control valve assembly is disclosed wherein the positioner is mounted internally to thus protect the positioner from damage stemming from environmental, impact, or other outside influences. Accordingly, not only can the position of the valve be accurately measured, but the sensing hardware is less subjected to damage or other drawbacks associated with exposure.

Abstract: An actuating device for hydraulically securing a camshaft of an engine of a motor vehicle in a start position has a solenoid valve controlling the flow of a pressure medium to a camshaft adjuster with a rotary slide valve that is fixedly connected to the camshaft and moves the camshaft into the required start position according to the pressure medium supplied to it by the solenoid valve.

Abstract: A valve control system for positioning a valve in response to a command signal. The valve control system comprises a sensor for detecting the position of the valve and for generating an outer feedback signal, a valve location command circuit for comparing the command signal to the outer feedback signal to generate a correction signal, an actuator for positioning the valve in response to pneumatic pressure, a spool slidably disposed within a block to direct pneumatic pressure to the actuator, a spool positioning device for moving the spool to a desired position, a spool sensor for detecting the current position of the spool and generating an inner feedback signal, and a spool location command for comparing the correction signal to the inner feedback signal to generate a spool positioning signal to direct the spool positioning device to move the spool to the desired position.

Abstract: A hydraulic drive unit has a tracking regulator valve (19) for controlling a servo drive (18) of a main control valve (16), where the main control valve controls flow to a hydraulic motor (11). The tracking regulator valve is controlled by an actuating element (42), which is controlled by a comparison of a nominal position value, set by an electric motor (36), and an actual position valve, generated by a mechanical feedback (53) connected to the hydraulic motor. The main control valve includes a slide valve piston (87), which forms a housing for the tracking regulator valve, which has two piston slide valve elements (39, 41). The slide valve piston (87) of the main control valve (16) has an axial through-bore (122) through which passes the actuating element.

Abstract: A closed loop hydraulic system especially adapted as a shot control system for a die casting machine. The control system includes a voice coil driven pilot servo valve mounted to a high flow proportional valve. The control system provides a highly controllable restriction of the outflow of hydraulic fluid from a hydraulic shot cylinder which drives a shot plunger of a die casting machine. Position transducers are provided for the pilot servo valve, proportional spool valve, and shot cylinder and a control system monitors these inputs to provide closed loop control over the shot process. A hydraulic accumulator is located in each of the pressure source and return lines of the pilot servo valve and a hydraulic accumulator tank is mounted directly to the proportional valve.

Abstract: In a pneumatic control circuit, five three-port, two-position, directional control valves, three of which have manual controls, and two shuttle valves are arranged for controlling a first pneumatic device and a second pneumatic device in an operating mode wherein the second pneumatic device cannot be readily enabled before the first pneumatic device is enabled. A first control valve having a manual control is arranged to control the first pneumatic device. A second control valve having a pilot valve is arranged to control the second pneumatic device. A pilot control valve having a manual control is arranged to connect the first control valve to the pilot valve of the second control valve via a shuttle valve. A holding control valve has a cam control, which is operated by the second pneumatic device, and has an outlet connected to the pilot valve of the second control valve.

Abstract: In a stability compensating mechanism of an electro-hydraulic servo system which includes a load-displacement detecting unit for detecting a displacement of a piston of actuator or a displacement of a load connected to the piston, and a control valve for supplying a hadraulic oil to the actuator to drive the load and in which a piston-displacement detection signal of the load-displacement detecting unit is fed as a feedback signal back to a forward circuit and the control valve is operated by a deviation signal between the feedback signal and a command signal, the stability compensating mechanism comprising a valve-displacement detecting unit for detecting a valve displacement of the control valve and outputting a valve-displacement detection signal representative of the valve displacement, and a load-pressure computing unit for computing a load pressure that is acted on the actuator due to the load, on the basis of the piston-displacement detection signal of the load-displacement detecting unit and the valve

Abstract: A control system for a hydraulic drive element such as a cylinder for a press includes a pilot valve having a plurality of fluid outlets controlled by a pilot valve spool unidirectionally biased by a resilient spring at one end thereof to a neutral position. A main valve having an elongated main valve spool resiliently biased to a center position. The opposite ends of the main valve spool are contiguous with individual pressure chambers separately connected to one of the plurality of outlets of the pilot valve. A link engaged with an end of the pilot valve spool which is opposite the end engaged by the resilient spring. A set value drive including stepping motor is coupled to the link for moving the pilot valve spool in either of opposite directions from the neutral position. The link is coupled for movement by the main valve spool to return the pilot valve spool to the neutral position.

Abstract: A drive for a steam servo valve (2), including a control valve arrangement for regulating the actuating pressure of a servo drive (1), whereby the drive can always be actuated reliably and quickly even with comparatively high oil pressure. This is achieved by the control valve arrangement having at least two regulatable control valves (17, 21) which are pressure-actuated via at least one pilot regulating valve (proportional pressure valve 29, 34).

Abstract: A 3/2 proportional control valve is provided with an actuating piston which is subjected to the control pressure set in a pilot valve. The area relationships of the actuating piston are so chosen that at the actuating piston a high pressure gradient obtains and the adjustment dynamics of the regulating piston are increased.

Abstract: A pneumatic control system for a reversible stepping actuator has an analog pneumatic control signal and an analog signal indicative of actual position of the actuator. Imbalance in these signals opens one or the other of a pair of comparator valves having inlets connected to a source of pneumatic pressure. Opening of either of the comparator valves enables a pulse timer which converts the pneumatic pressure from either of the comparator valves to pulses of pneumatic pressure applied to one or the other of the operators of the reversible stepping actuator. An oscillating pneumatic timer may be used to produce the pressure pulses, or an electric timer can be used to "chop" one of the pneumatic pressures into periodic pulses.

Abstract: A servovalve includes a flow-control valve connectable between a source of fluid pressure and a load and having a spool displaceable between an open position permitting fluid flow between the load and the source and a closed position axially offset therefrom and blocking such flow. A pilot valve has an impact plate and a pair of nozzles operatively axially oppositely effective on the spool and oppositely flanking the plate. Thus when the plate is closer to one of the nozzles than to the other the spool is axially displaced into one of its positions and when the plate is closer to the other nozzle the spool is urged axially oppositely. A solenoid-type servomotor is connected to the impact plate to move same between the nozzles so that when it is close to one nozzle it blocks flow therefrom and allows pressure to build up on the corresponding end of the spool, while the other nozzle is opened to reduce pressure at the corresponding spool end.

Abstract: An electro-hydraulic servo valve of two-stage type including a beam mounted for swinging movement with respect to the casing of the valve. One portion of the beam is engaged with the second-stage displaceable element of the valve and another portion of the beam carries an electrical sensor through which an electrical current is caused to pass. Magnet means are housed in the casing adjacent the other portion of the beam. As, on controlled movement of the displaceable element, the beam swings, the positional relationship of the sensor with respect to the magnetic fields of the magnet means changes, thus to so vary the electrical potential across the sensor that an electrical feedback signal is emitted by the sensor which is proportional to the displacement of said displaceable element.

Abstract: A positioner-actuator control system includes a pair of relays and a pivotally mounted beam for operation thereof in response to a pneumatic control signal. A summing beam has forces applied to it from an input signal, a controlled device position lever, a zero adjustment and a damping mechanism comprising a pair of flat springs attached to the relay beam and to the summing beam. A clamp is movable along the flat springs to permit user adjustment of the damping force.

Abstract: A two-stage pneumatic servo valve assembly for controlling an output motor is disclosed. An input device, such as a torque motor, is coupled to the two-stage servo valve assembly. The first stage of the servo valve assembly includes a vane valve movable by the output of the torque motor to selectively provide a fluid path from an input source to one of the first-stage output channels. The first-stage pneumatic servo valve is coupled with a second stage servo valve. The second stage servo valve controls fluid flow from a pneumatic fluid source to an output motor. The second stage servo valve includes a slidable spool valve movable by fluid received from the first-stage servo valve. A feedback control from the second-stage servo valve to the first-stage servo valve is provided. A second feedback control is provided from the output of the output motor to the first stage servo valve.

Abstract: An improvement in a servovalve employing spool-valve-position feedback provided by a feedback spring, wherein the feedback spring centerline is not aligned vertically with the center line of the spool valve, comprising a receiving hole in the spool valve body and a slot in the spool for feedback spring clearance; a pin or ball rigidly attached to the feedback spring with the portions of the pin or the ball which contact the sides of the receiving hole fitting in face to face relation to the inner surface of recesses formed in the slot by the hole.

Abstract: This invention relates to an automatic temperature control system for automobiles and improved components thereof. The control system operates on the proportional stroke principle and comprises an in-car air sensing tube biased with ambient air; a sensor in an aspirator at the end of the tube; a moving pivot operated directly by the output of the sensor; and a feedback valve operated by the moving pivot for driving a vacuum-assist motor, the output stroke of which operates the various electrical and vacuum functions of the heater-air conditioning system.

Abstract: A low friction servo valve having a housing which contains therein an input shaft, a pair of slidably mounted valve spools and an actuator. Mechanical input is received by the input shaft in order to provide rotational displacement thereof. This displacement is transferred to a flapper portion on the input shaft which operates in conjunction with a pair of jet nozzles. Movement of the flapper causes pressure buildup in one of the jet nozzles which in turn causes sequential movement of the pair of valve spools to take place. Operation of the actuator is dependent upon movement of one of the valve spools, with this valve spool also being connected to the input shaft for assisting in the rotational displacement thereof as well as being connected to a feedback spring which forces the flapper to assume its neutral position thereby reducing the pressure buildup in one of the jet nozzles.

Abstract: An electrohydraulic servovalve having a pair of linear, variable, differential transducers (LVDT) affixed thereto in side by side relationship. A spool valve driven by the electrohydraulic servovalve is connected to the movable core in each of the LVDTs so that as the spool valve moves, each of the LVDTs develops a position output signal representative of the position of the spool. The connecting mechanism between the driven spool valve and the LVDT cores is a rod which is attached to the spool and includes a pair of flanges at the opposite end defining a groove therebetween. A pair of plates spaced apart at the center define a slot centrally thereof. The plates at the slot are spaced apart so that the width of the two plates plus the space between them is greater than the width of the groove in the rod. The outermost flange is formed so that it will fit through the slot in the plates. The two cores of the LVDTs include rods which are in turn permanently affixed at each end of the plates.

Abstract: The dynamic performance of hydraulic apparatus including a fluid-operated actuator controlled by a servo-controller, is improved by providing phase lead compensation to the controller in response to movement of the movable element of the actuator so that the low frequency response of the apparatus is raised.

Abstract: An electrohydraulic servovalve including a second stage piston slidably mounted within a housing and movable responsive to application of pressure signals thereacross to control the flow of fluid under pressure from a source to a load in response to electrical input signals applied to the servovalve. The electrical signals are applied to a torque motor which has a driven member affixed thereto which generates the pressure signals applied to the spool. A mechanical feedback member is connected between the driven member and the spool. The mechanical feedback member is part of an assembly which is removably attached to the driven member. The removable attachment includes a tang extending radially from the driven member which receives a holder to which the feedback member is permanently affixed. The holder includes opposed flanges one of which receives the tang through an indexing opening provided therein.

Abstract: A conventional control valve hydraulically powered by a double acting cylinder and controlled electrically through a double acting solenoid supplied by a variable D.C. supply. The solenoid transmits varying forces to a four-way pilot valve which in turn controls the positioning of the double acting cylinder. The de-energized solenoid, control valve spool and pilot spool are neutrally balanced between two springs equally loaded with differing spring rates so that a small movement of the solenoid core will cause a proportionally larger movement of the main control valve spool proportioned to the different spring rates.

Abstract: A control system for a fluid powered actuator arrangement which includes two drivingly interconnected hydraulic actuator devices, comprises two control valves which are movable in unison to apply operating pressure to the respective devices. The control valves being reponsive to four electro-hydraulic pilot valves, each of which is controlled by four nominally identical electrical input signals. The control system includes means for monitoring the electrical input signals and the operating pressures, and for isolating or rendering inoperative parts of the system in response to several combinations of malfunction indication.

Abstract: A thermopneumatic actuator of the invention is used to control an automobile heater and/or air conditioner to maintain a desired temperature in the automobile passenger compartment through a mechanical output member of the actuator. The output member is connected to and moved by a diaphragm which is positioned by vacuum introduced from the automobile intake manifold and works against a diaphragm spring. A valve is controlled by a bimetal spring exposed to air from the passenger compartment to modulate the vacuum applied to the diaphragm. A feedback spring connected between the diaphragm and the valve works against the bimetal spring. An aspirator comprising a venturi tube causes air flow from the passenger compartment around the bimetal spring.

Abstract: A combined feedback control system for a servo actuator including a ram that produces a mechanical displacement output of the system as directed by a position command signal. In the combined feedback control system a lever arrangement mechanically combines displacement and velocity information of the ram, and such combined information is conveniently transduced and electrically combined with the position command signal to develop an error signal that controls an electro-hydraulic valve. The latter preferably through a fluid amplification stage controls the delivery of fluid to the ram and, thus, the position thereof. Through the lever arrangement a mechanical failure control is operative to move the ram to a predetermined position upon failure of the electro-hydraulic valve and a manual control is operable to control the ram position via the fluid amplification stage.

Abstract: This invention relates to an automatic temperature control system for automobiles and improved components thereof. The control system operates on the proportional stroke principle and comprises an in-car air sensing tube biased with ambient air; a sensor in an aspirator at the end of the tube; a moving pivot operated directly by the output of the sensor; and a feedback control valve operated by the moving pivot for driving a vacuum-assist motor, the output stroke of which operates the various electrical and vacuum functions of the heater-air conditioning system.

Abstract: A temperature control apparatus of an air conditioner for automobiles, which comprises a blower for feeding air through a cooling unit and a heating unit disposed in an air passage, an air mix door for controlling the amount of air passing through the heating unit, an actuator for actuating said door, a negative pressure source for applying a negative pressure to said actuator through a controller, a sensor emitting a negative pressure signal in response to the temperature in a cab of an automobile and a regulator emitting a negative pressure signal in response to the change of the position of said door, wherein the output negative pressure signal of the temperature sensor is compared with the output negative pressure signal of the regulator by said controller and a negative pressure is applied to the actuator according to a deviation between said two output signals to control the degree of opening of said air mix door so as to maintain the temperature in the cab at a substantially constant level.